Text Representations of R Objects

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Description

This function takes a vector of names of R objects and produces text representations of the objects on a file or connection. A dump file can usually be sourced into another R session.

Usage

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dump(list, file = "dumpdata.R", append = FALSE,
     control = "all", envir = parent.frame(), evaluate = TRUE)

Arguments

list

character vector. The names of one or more R objects to be dumped.

file

either a character string naming a file or a connection. "" indicates output to the console.

append

if TRUE and file is a character string, output will be appended to file; otherwise, it will overwrite the contents of file.

control

character vector indicating deparsing options. See .deparseOpts for their description.

envir

the environment to search for objects.

evaluate

logical. Should promises be evaluated?

Details

If some of the objects named do not exist (in scope), they are omitted, with a warning. If file is a file and no objects exist then no file is created.

sourceing may not produce an identical copy of dumped objects. A warning is issued if it is likely that problems will arise, for example when dumping exotic or complex objects (see the Note).

dump will also warn if fewer characters were written to a file than expected, which may indicate a full or corrupt file system.

A dump file can be sourced into another R (or perhaps S) session, but the function save is designed to be used for transporting R data, and will work with R objects that dump does not handle. For maximal reproducibility use control = c("all", "hexNumeric").

To produce a more readable representation of an object, use control = NULL. This will skip attributes, and will make other simplifications that make source less likely to produce an identical copy. See deparse for details.

To deparse the internal representation of a function rather than displaying the saved source, use control = c("keepInteger", "warnIncomplete", "keepNA"). This will lose all formatting and comments, but may be useful in those cases where the saved source is no longer correct.

Promises will normally only be encountered by users as a result of lazy-loading (when the default evaluate = TRUE is essential) and after the use of delayedAssign, when evaluate = FALSE might be intended.

Value

An invisible character vector containing the names of the objects which were dumped.

Note

As dump is defined in the base namespace, the base package will be searched before the global environment unless dump is called from the top level prompt or the envir argument is given explicitly.

To avoid the risk of a source attribute becoming out of sync with the actual function definition, the source attribute of a function will never be dumped as an attribute.

Currently environments, external pointers, weak references and objects of type S4 are not deparsed in a way that can be sourced. In addition, language objects are deparsed in a simple way whatever the value of control, and this includes not dumping their attributes (which will result in a warning).

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

dput, dget, write.
save for a more reliable way to save R objects.

Examples

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x <- 1; y <- 1:10
dump(ls(pattern = '^[xyz]'), "xyz.Rdmped")
print(.Last.value)
unlink("xyz.Rdmped")

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